PROCEDURE:
1. Preheat oven to 375 degrees.
2. Unfold dough onto a lightly floured piece of parchment.
3. Cut into a 10-by-9-inch rectangle (if necessary, roll out slightly first).
4. Transfer dough on parchment to a baking sheet.
5. Use the tip of a sharp knife to score a 1-inch border (do not cut all the way through). Prick center all over with the tines of a fork.
6. Freeze 15 minutes.
7. Brush border of tart with beaten egg.
8. Bake until puffed and golden, about 25 minutes.
9. Remove from oven and press center down to create a hollow center.